I used to play the electric bass. I took up the double bass about four years ago.
My advice is:
1. Rent your first instrument. Ideally, rent from a place that has some kind of focus on double bass. Plywood is fine, but the generic plywood basses from a generalist classical music store are often set up terribly, with the wrong and nasty strings, inch high string height, sound post poorly positioned, etc. It's a tough enough instrument to play without making it harder with poor set-up. Make sure that it is set up correctly for the style you want to play. Strings are critical. Probably start with Spirocores for jazz, with a bit of arco for intontation. You don't say where your small town is, but maybe see if some of the big name double bass stores do long distance rental?
2. Even if you don't want to play classical, rent or buy a bow. Playing arco (ie, with a bow) will get your intonation right much more quickly than if you only play pizz. You will sound horrible with a bow to start. Just commit, and work through that.
3. Get a teacher. Even if you have to travel a couple of hours or more for a first lesson, and can only have a lesson a month. Or get skype lessons, or something. It is a really different instrument from electric bass, and you don't want to be trying to use your electric bass method on the double bass. You need to use double bass fingering if you are going to play in tune, you need to get hand and wrist position right. And you need to get your right hand pizz technique right if you are going to sound good, and not thin and weedy.
4. It is a completely different instrument from the electric bass. And the transition can be hard. Don't let this dishearten you, because it can really be worth it. I thought I would transition easily. Same tuning, same function - how hard could it be. And yet - hard. The transition from guitar to electric bass was vastly easier. The electric bass is almost in the guitar family, where the double bass is more in the violin family. People may or may not agree with that historically, but when you are thinking about playing, it is useful - you are changing family of instrument.
5. Don't worry about pickups or amplification or anything for the first year or more. When you decide to stick with it, and hunt for your own bass, you find the right bass and then find a pickup that suits you. All the pickups can be added to all of the instruments.
6. You may be tempted to get an electric upright bass. I'd recommend not. They are not much like a double bass, really. More like a fretless electric on a stick. You can pick up a little technique, but you'll still face quite a jump when you go to a full double bass.
7. It is a wonderful thing. It's a big, inconvenient, physically challenging instrument to play. But it really sounds great. And your connection to it is so physical. It's not a string vibrating in a magnetic field, causing a paper cone to vibrate somewhere behind you. It's a big wooden box resting against your stomach and your knee, and the whole thing vibrates in sympathy to generate the sound.
Good luck!
Anthony